When Greg and Colin Strause rolled into Hall H at Comic-Con this year with a movie no one had heard of, they knew if they didn’t have the goods, their movie could suffer insurmountable backlash. Thankfully, the footage they showed from Skyline was not only impressive, but the story the Strause’s told – about making the film on their own, on a relative shoe string budget, much like Paranormal Activity and The Blair Witch Project – was incredible. That these brothers, who also happen to own their own visual effects house, Hydraulx, made a movie that looks like it costs $200 million for a tiny fraction of that was jaw-dropping.

So it’s no surprise to report that, with the film just weeks away from its November 12 release date, the confident Strause Brothers are already working on the sequel. Details after the jump.

Film School Rejects did an interview with Colin and Greg Strause who said they have a 45 page treatment ready to go on a sequel to Skyline and that, if the film makes a “tenth” of what a normal event movie does, it’ll be deemed profitable enough to move ahead with. That’s not to say that there’s a guarantee Skyline 2 will happen, but, it’s in the works.

So let’s say a normal event film ends up making $300 million, which is roughly what Iron Man 2 made this year. A tenth of that is $30 million. With the amount of marketing Universal is putting into Skyline -I can’t walk around the block without seeing a billboard or flip a channel without seeing the commercial – it’s almost certain to make that, if not in the first weekend. Is roughly $30 million what the film cost, though? No one has gone on record with a budget.

What has been put on record is the fact that Sony, who used Hydraulx to do effects for Battle: Los Angeles – scheduled for March 2011 release – accused the company of stealing effects and using them in Skyline. After all, both films are about the alien destruction of the City of Angels. Depending on what happens with that, maybe some of the Skyline profits will end up going to legal fees before the sequel gets the green light. That’s speculative though and more information will certainly become available once Skyline opens on November 12.

For me, the best thing that could happen with Skyline is that it be a huge hit, 20th Century Fox looks on their shelves and goes, “Oh yeah, we have a movie like this, Independence Day 2!” and that gets made. With Roland Emmerich directing, it’s not going to cost $20 or $30 million dollars though – more like ten times that – but I still can’t wait to see it.

Are you guys excited for Skyline? Do you think the marketing is working? And does the story of the Strause brothers making this movie inspire you as a filmmaker?